Resin coated metal sheet

ABSTRACT

A resin coated metal sheet of the invention has an epoxy resin layer on a galvanized metal sheet, wherein the resin layer contains iron phosphide and at least one selected from the group consisting of aluminum triphosphate, calcium ion exchange silica and amorphous magnesium silicate compound. In the resin coated metal sheet, the epoxy resin is an urethane modified epoxy resin and/or dimer acid modified epoxy resin, and the iron phosphide has a maximum particle diameter of 15 μm or less. The resin coated metal sheet has excellent weldability, formability and corrosion resistance.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention belongs to the technical field of a resincoated metal sheet, specifically, the technical field of a resin coatedmetal sheet having an epoxy resin layer on a galvanized metal sheet,particularly a coated steel sheet for automobiles which enables theomission of part of a coating step in the production of an automobileand the omission of the filling of a grease into a bent portion or thelike.

[0003] 2. Description of the Related Art

[0004] JP-A 11-5269 (the term “JP-A” as used herein means an “unexaminedpublished Japanese patent application”) discloses a resin coated metalsheet having a resin coating layer on a galvanized metal sheet oraluminum plated metal sheet.

[0005] Although a resin, a curing agent and conductive pigment containedin a coating are set forth in claims of JP-A 11-5269, corrosionpreventing additives are merely enumerated in the section “DetailedDescription of the Invention”.

[0006] Expressions for the thickness “t” (μm) of a coating film and thecontent “P” (wt %) of the conductive pigment in the coating film aregiven in claims of JP-A 11-5269. These expressions are the followingexpressions (1) and (2). In these expressions (1) and (2), when t=7,39≦P≦71.

P≧7.14t−10.71   (1)

P≦7.14t+21.43   (2)

[0007] Epoxy resin, urethane resin, acrylic resin, polyester resin andmodified resins thereof are disclosed as the resin. Isocyanate compoundsand/or alkyl etherified amino formaldehyde resin (alkylated melamineresin) are disclosed as the curing agent.

[0008] JP-A 2000-522923 discloses a coating composition (coating film)for covering an amorphous metal.

[0009] Types and amounts of a resin, curing agent, rust-proof pigmentand conductive pigment are defined in claims of JP-A 2000-522923.

[0010] Epoxy resin (including epoxy resin having an epoxy group such asdimer acid modified epoxy resin)+blocked polyurethane resin aredisclosed as the resin. Guanidine, substituted guanidine, substitutedurine, cyclic tertiary amine and mixtures thereof are disclosed as thecuring agent. A silicate compound (0 to 15 wt %) is disclosed as therust-proof pigment. Zinc, aluminum, graphite and/or molybdenumdisulfide, carbon black and iron phosphide (40 to 70 wt %) are disclosedas the conductive pigment. The amount of the solvent is 0 to 30 wt %.

[0011] The patent JP-A 11-5269 discloses the relationship among thethickness of the coating film, the amount of the conductive pigment,weldability, formability and adhesion but not corrosion resistance whichis an important evaluation item in examples at all and attachesimportance to weldability and formability. Therefore, it is unknownwhether the resin coated metal sheet of the above patent document 1 hasexcellent corrosion resistance or not.

[0012] Meanwhile, JP-A 2001-522923 mainly describes corrosion resistanceand fails to disclose weldability and formability. Therefore, it isunknown whether the coating composition of the above patent document hasexcellent weldability and corrosion resistance.

[0013] Consequently, it is unknown whether what are disclosed by theabove patent documents are excellent in all of weldability, formabilityand corrosion resistance and it is possible that they are not excellentin any one of them.

SUMMARY OF THE INVENTION

[0014] In view of the above situation, it is an object of the presentinvention to provide a resin coated metal sheet which has excellentweldability, formability and corrosion resistance.

[0015] The inventors of the present invention have conducted intensivestudies to attain the above object and have accomplished the presentinvention. The present invention relates to a resin coated metal sheethaving excellent weldability, formability and corrosion resistance and amanufacturing process thereof, which can attain the above object.

[0016] The present invention which has been accomplished and couldattain the above object relates to a resin coated metal sheet which hasthe following constitutions.

[0017] That is, the resin coated metal sheet according to the presentinvention is a resin coated metal sheet comprising: a metal sheet; and aresin layer comprising an epoxy resin which is formed on the metalsheet, wherein said resin layer contains iron phosphide; at least oneselected from the group consisting of aluminum triphosphate, calcium ionexchange silica and amorphous magnesium silicate compound; and a curingagent.

[0018] In the resin coated metal sheet according to the aboveconstruction, the metal sheet can be a galvanized steel sheet.

[0019] In the resin coated metal sheet according to the aboveconstruction, the epoxy resin can be at least one of a urethane modifiedepoxy resin and a dimer acid modified epoxy resin.

[0020] In the resin coated metal sheet according to the aboveconstruction, the content of the iron phosphide is preferably 40 to 55wt %, and the content of the at least one selected from the groupconsisting of aluminum triphosphate, calcium ion exchange silica andamorphous magnesium silicate compound is preferably 5 to 25 wt %.

[0021] In the resin coated metal sheet according to the aboveconstruction, the maximum particle diameter of the iron phosphide ispreferably 15 μm or less.

[0022] The resin coated metal sheet of the present invention isexcellent in weldability, formability and corrosion resistance.Therefore, it is suitable for use as a material (resin coated metalsheet) for applications in which welding and processing are carried outand corrosion resistance is required.

BRIEF DESCRIPTION OF THE DRAWINGS

[0023]FIG. 1 is a schematic diagram showing the appearance of anoverlapping sample used in a corrosion resistance evaluation test on theresin coated metal sheets of Examples and Comparative Examples of thepresent invention when seen from the front.

[0024]FIG. 2 is a schematic diagram showing the appearance of anoverlapping sample used in a corrosion resistance evaluation test on theresin coated metal sheets of Examples and Comparative Examples of thepresent invention when seen from the side.

[0025]FIG. 3 is a diagram showing the corrosion resistance test cycle ofthe resin coated metal sheets of Examples and Comparative Examples ofthe present invention.

[0026]FIG. 4 is a schematic diagram of a bending test apparatus.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0027] Basically, the present invention optimizes the type of aconductive coating and the type of a corrosion preventing additive andfurther the amount and particle diameter of the conductive coating andthe amount of the corrosion preventing additive in order to obtain aresin coated metal sheet having excellent weldability, formability andcorrosion resistance.

[0028] In the resin coated metal sheet of the present invention, ironphosphide which is a conductive filler is contained and at least oneselected from the group consisting of aluminum triphosphate, calcium ionexchange silica and amorphous magnesium silicate compound is containedas a corrosion preventing additive (to be referred to as “corrosionpreventing additive of the present invention” hereinafter).

[0029] When iron phosphide is contained, excellent weldability andformability are obtained. When the corrosion preventing additive of thepresent invention is contained, excellent corrosion resistance isobtained. Therefore, the resin coated metal sheet of the presentinvention has excellent weldability, formability and corrosionresistance.

[0030] Further, the amount and particle diameter of the above conductivecoating and the amount of the corrosion preventing additive areoptimized to enable the further improvement of weldability, formabilityand corrosion resistance.

[0031] The conductive filler is added to improve weldability. When ironphosphide is used as the conductive filler, not only weldability butalso formability can be improved. A zinc (Zn) rich paint which isgenerally used to obtain a corrosion protecting effect and conductivityhas a problem with formability because powdering readily occurs at thetime of processing.

[0032] When the amount (content) of iron phosphide as the conductivefiller is larger than 55% by mass (wt %), formability deterioratesthough weldability is satisfactory. When the content is lower than 40 wt%, weldability deteriorates though formability is satisfactory.Therefore, the content of iron phosphide is desirably 40 to 55 wt %.

[0033] When the maximum particle diameter of iron phosphide as theconductive filler is larger than 15 μm, formability degrades. Therefore,the maximum particle diameter of iron phosphide is desirably 15 μm orless. The particle diameter of iron phosphide may be small. However, thelower limit of particle diameter is 6 μm, since iron phosphide having aparticle diameter of 6 μm or less is hardly acquired.

[0034] A corrosion protecting agent is added to provide corrosionresistance. When the corrosion protecting agent of the present invention(at least one selected from the group consisting of aluminumtriphosphate, calcium ion exchange silica and amorphous magnesiumsilicate compound) is contained, excellent corrosion resistance isobtained. Out of these three, aluminum triphosphate and amorphousmagnesium silicate compound have a larger effect of improving corrosionresistance than calcium ion exchange silica and preferred in thisrespect.

[0035] When the amount (content) of the corrosion preventing additive ofthe present invention is larger than 25 wt %, formability deterioratesand when the content is lower than 5 wt %, corrosion resistance cannotbe obtained. Therefore, the content of the corrosion preventing additiveof the present invention is desirably 5 to 25 wt %. When only one of theabove three substances is contained, the content of the corrosionpreventing additive of the present invention is the content of thesubstance and when two or more of the above three substances arecontained, the content of the corrosion preventing additive is the totalcontent of these (total of the contents of the substances).

[0036] The upper limit of particle diameter of the corrosion preventingadditive of the present invention is desirably 10 μm which is about thethickness of the coating film. This is because when the particlediameter of the corrosion preventing additive is larger than 10 μm,formability deteriorates.

[0037] Aluminum triphosphate exhibits excellent corrosion resistance dueto the buffering function of pH and the formation of an immobile film.Though only aluminum triphosphate is used, aluminum triphosphateproducts treated with Mg and Ca may be used and are preferred. This isbecause they can exhibit more excellent corrosion resistance.

[0038] Calcium ion exchange silica exhibits more excellent corrosionresistance due to the buffering function of PH. The content of calciumin the calcium ion exchange silica is generally 1 to 10%.

[0039] The amorphous magnesium silicate compound exhibits corrosionresistance due to the buffering function of pH and the formation of animmobile film. The amorphous magnesium silicate compound is produced byfiltering a precipitate formed by reacting an alkali metal-silicate witha water-soluble magnesium salt in an atomic Mg/Si ratio of 0.025 to 1.0in an aqueous solution, rinsing, drying and grinding it. It can beconfirmed by X-ray diffraction that the compound is amorphous.

[0040] An epoxy resin is used as the resin for the resin layer in thepresent invention. This epoxy resin is preferably a flexible epoxy toimprove formability (powdering resistance at the time of processing).The flexible epoxy is an epoxy which can be bent 300 times or morebefore it is broken in an MIT flexural test. The MIT flexural test wascarried out by sandwiching one end of a specimen having a width of 15 mmand a length of 130 mm with the clamp of a testing device shown in FIG.4 to bend it and moving the other end of the specimen at a tension of 1kgf, a turning angle of 135° and a rotational vibration of 175 times/minto measure the number of times of bending before it was broken.

[0041] The above flexible epoxy is preferably one of the following epoxyresins:

[0042] (1) Urethane Modified Epoxy Resin:

[0043] This resin is obtained by introducing a urethane bond (resin)into the molecular structure of an epoxy resin so that flexibility isprovided by the urethane resin structure.

[0044] (2) Dimer Acid Modified Epoxy Resin:

[0045] This resin is, for example, a mixture of the Epicoat 1007bisphenol A type epoxy resin (trade name, manufactured by Japan EpoxyResin Co., Ltd.) and the Epicoat 872 dimer acid modified epoxy resin(trade name, manufactured by Japan Epoxy Resin Co., Ltd.) in a ratio of2/1.

[0046] In the present invention, blocked isocyanate, melamine resin oramine hardener is used as the curing agent. Out of these, blockedisocyanate and melamine resin react with the hydroxyl group of the epoxyresin. The amine hardener reacts with the epoxy group of the epoxyresin. The ratio of the equivalent of the reactive group in the epoxyresin to the equivalent of the reactive group in the curing agent ispreferably 0.8 to 1.2.

[0047] The above blocked isocyanate, melamine resin and amine hardenerare described hereinunder.

[0048] (1) Blocked Isocyanate:

[0049] This is obtained by blocking an isocyanate group with caprolactamor oxime. A blocking agent is dissociated at around 150° in the case ofcaprolactam. A blocking agent is dissociated at 120 to 130° in the caseof oxime.

[0050] (2) Melamine Resin:

[0051] Examples of this melamine resin include n-butyletherifiedmelamine resin, isobutyletherified melamine resin and methyletherifiedmelamine resin.

[0052] (3) Amine Hardener:

[0053] This amine hardener is, for example, an aliphatic polyamine,alicyclic polyamine, aromatic polyamine or polyamide amine. Specificexamples of these are given below.

[0054] <aliphatic polyamine>: diethylene triamine, dipropylene triamine,triethylene tetramine, tetraethylene pentamine, dimethylaminopropylamine, diethylamino propylamine, dibutylamino propylamine,hexamethylene diamine, N-aminoethyl piperazine, bis-aminopropylpiperazine, trimethylhexamethylene diamine, etc.

[0055] <alicyclic polyamine>:3,3′-dimethyl-4,4′-diaminodicyclohexylmethane,3-amino-1-cyclohexylaminopropane, 4,4′-diaminodicyclohexylmethane,isophoronediamine, 1,3-bis(aminomethyl)cyclohexane,N-dimethylcyclohexylamine, heterocyclic diamines, etc.

[0056] <aromatic polyamine>: xylylene diamine,4,4′-diaminodiphenylmethane, 4,4′-diaminodiphenyl ether,diaminodiphenylsulfone, m-phenylenediamine, etc.

[0057] <polyamide amine>: also called “polyamide resin” or “polyaminoamide”.

[0058] In the present invention, a galvanized metal sheet is preferablyused as a base material (base sheet) to be covered with a resin layer.This galvanized metal sheet is obtained by galvanizing a metal sheet.The type of this metal sheet and the galvanizing method are notparticularly limited, and various metal sheets and various galvanizingmethods may be used. For example, an electro-galvanized steel sheet (EG)and galvannealed steel sheet (GA) may be used. When anelectro-galvanized steel sheet is used, it is important to form anundercoat (treatment with a chromate or non-chromate (phosphoricacid-based)) before the formation of the resin layer. When agalvannealed steel sheet is used, an undercoat is not always necessaryand may be or may not be formed. Other materials, such as aluminumplated steel sheet, zinc/aluminum plated steel sheet,zinc/aluminum/magnesium plated steel sheet, aluminum sheet and so on,can be used as the base material in the present invention.

EXAMPLES

[0059] Examples and Comparative Examples of the present invention willbe provided hereinbelow. The present invention is not limited to theseexamples, and various changes and modifications may be made in thepresent invention without departing from the spirit and scope thereofand all are included in the technical scope of the present invention.

[0060] [1] Manufacture of Resin Coated Metal Sheet (Coating Procedure)

[0061] A galvannealed steel sheet having a non-chromate undercoat wasprepared as the galvanized metal sheet which is a base material (basesheet). A resin layer was formed on this metal sheet to manufacture aresin coated metal sheet. This will be described in more detailhereinbelow.

[0062] (1) After the resin and the curing agent were mixed together in apredetermined ratio, iron phosphide (FeP) which is a conductive filler,corrosion preventing additive and anti-settling agent were added to theabove mixture. The types of the resin and the curing agent used and themixing ratio of these are shown in Table 1. The mixing ratio of FeP as aconductive filler and the type and mixing ratio of the corrosionpreventing additive and the mixing ratio of the anti-settling agent areshown in Table 2.

[0063] A coating was prepared from the thus obtained mixture. That is,the mixture was added to a mixed solvent of xylene, propylene glycolmonomethyl ether acetate and n-butanol in a ratio of 4/3/1, dissolvedand dispersed in the mixed solvent to a solid content of 50% to obtain acoating.

[0064] (2) The thus obtained coating was stirred by a homogenizer at 300rpm under cooling for 10 minutes.

[0065] (3) A bar coater was selected and the above coating was appliedto the galvannealed steel sheet having a non-chromate undercoat to atarget coating thickness of 10 μm.

[0066] (4) This coated steel sheet was heated in a continuous heatingfurnace at a PMT (the maximum temperature of the steel sheet) of 230° C.to remove the solvent and cure the coating film so as to obtain a resincoated metal sheet.

[0067] [2] Evaluation of Resin Coated Metal Sheet

[0068] The thus obtained resin coated metal sheet was tested for theevaluation of formability, weldability and corrosion resistance. Theevaluation test methods will be described hereinunder.

[0069] A. Formability

[0070] (1) Cylindrical drawing was carried out under the followingconditions.

[0071] <Cylindrical Drawing Conditions>

[0072] blanking diameter of resin coated metal sheet (blank diameter forcylindrical drawing): 90 mm

[0073] punch diameter (outer diameter): 50 mm

[0074] die diameter (inner diameter): 52 mm

[0075] BHF (blank holder force, i.e. crinkling suppressing pressure):980N

[0076] Cylindrical drawing rate: 160 mm/min

[0077] (2) A tape was forcedly removed from the surface after the abovecylindrical drawing. That is, an adhesive tape (Cellophane tape) wasaffixed to the surface of the cylindrical portion of a cylindricallydrawn product obtained by the above cylindrical drawing (bottomedcylinder) and forcedly removed.

[0078] (3) A reduction in the weight (W_(d)) of the above cylindricallydrawn product by affixing and removing the adhesive tape was measured.That is, the weight W₁ of the cylindrically drawn product before theadhesive tape was affixed to the product and the weight W₂ of thecylindrically drawn product after the adhesive tape was affixed andremoved was measured to obtain a weight difference between them(W₁−W₂=W₁−₂) which was divided by the surface area S_(d) of the adhesivetape affixed portion of the cylindrically drawn product so as to obtaina weight reduction W_(d) (=W₁−₂/S).

[0079] (4) The criteria of formability are given below.

[0080] <Criteria of Formability>

[0081] weight reduction W_(d): x, when it is 6 g/m² or more (poorformability)

[0082] weight reduction W_(d): Δ, when it is 5 g/m² or more and lessthan 6 g/m² (superior to × and allowable range)

[0083] weight reduction W_(d): O, when it is 3 g/m² or more and lessthan 5 g/m² (high formability)

[0084] weight reduction W_(d): ⊚, when it is less than 3 g/m² (superiorto O and excellent)

[0085] B. Weldability

[0086] This was evaluated based on electrode life time under thefollowing test conditions. That is, the welding was carried out on thesurface of a resin coated metal sheet (resin coated side) under thefollowing test conditions to obtain the number of spot welds so as toevaluate weldability.

[0087] <Test Conditions>

[0088] end diameter: 6 mm

[0089] pressure: 200 kgf

[0090] welding time: 12 cycles

[0091] welding current: 8.0 kA

[0092] (2) The criteria of weldability are given below

[0093] <Criteria of Weldability>

[0094] when the number of spot welds is smaller than 400: × (poorweldability)

[0095] when the number of spot welds is 400 or more and smaller than600: Δ (superior to × and allowable range)

[0096] when the number of spot welds is 600 or more and smaller than800: O (high weldability)

[0097] when the number of spot welds is 800 or more: ⊚ (superior to Oand excellent)

[0098] C. Corrosion Resistance

[0099] A corrosion resistance evaluation test is made on an overlappingportion.

[0100] (1) An overlapping sample was manufactured by using resin coatedmetal sheets and a spacer (thickness: 120 μm). FIG. 1 is a front view ofthis overlapping sample and FIG. 2 is a side view of the sample. Thefollowing treatments (in accordance with a general car coating method)were made on this overlapping sample.

[0101] a. alkali degreasing (with sodium orthosilicate at 40° C. for 2minutes)

[0102] b. rinsing (30 sec)

[0103] c. phosphating (60° C.×2 minutes)

[0104] d. ED [cation electrocoating: target thickness of 20 μm]

[0105] (2) 20 cycles of a corrosion resistance test shown in FIG. 3 wasmade on the sample subjected to the above treatments. One test cycle is1 week.

[0106] (3) After the above corrosion resistance test (20 cycles), thesample was opened to obtain the red rust growth ratio of the overlappingportion so as to evaluate its corrosion resistance based on thefollowing criteria. The rest rust growth ratio is the proportion of thesurface area of a red rust growing portion.

[0107] <Criteria of Corrosion Resistance>

[0108] red rust growth ratio: x, when it is 7% or more (low corrosionresistance)

[0109] red rust growth ratio: Δ, when it is 4% or more and less than 7%(superior to × and allowable range)

[0110] red rust growth ratio: O, when it is 1% or more and less than 4%(good corrosion resistance)

[0111] red rust growth ratio: ⊚, when it is less than 1% (superior to Oand excellent)

[0112] [3] Evaluation Results of Resin Coated Metal Sheets

[0113] The results of the above evaluation tests are shown in Table 3.The weldability and corrosion resistance of the resin coated metal sheetof Comparative Example 1 are evaluated as ⊚ (excellent) but theformability of the resin coated metal sheet is evaluated as × (poor).The formability and weldability of the resin coated metal sheets ofComparative Examples 2 and 3 are evaluated as ⊚ (excellent) but thecorrosion resistance of the resin coated metal sheets is evaluated as ×(low).

[0114] In contrast to this, the resin coated metal sheets of Examples 1to 12 of the present invention are excellent in overall properties(overall evaluation results of formability, weldability and corrosionresistance) and excellent in all aspects. That is, they are evaluated as⊚ in terms of formability, weldability and corrosion resistance(excellent formability, weldability and corrosion resistance) or O inany one of formability, weldability and corrosion resistance (goodformability, weldability and corrosion resistance) and ⊚ in the otherproperties.

[0115] The resin coated metal sheets of Examples 13 to 19 of the presentinvention are superior to the resin coated metal sheets of ComparativeExamples 1 to 3 in all aspects. That is, they are evaluated as Δ in anyone of formability, weldability and corrosion resistance and ⊚ in theother properties. TABLE 1 curing agent solid content) epoxy resin (solidcontent) butyl- urethane urethane dimer acid etherified modifiedmodified modified bisphenol A bisphenol A polyamide blocked blockedmelamine resin 1 resin 2 resin type resin 1 type resin 2 epoxy polyolamine isocyanate 1 isocyanate 2 resin examples 1-7 100 45 example 8 10025 example 9 100 27 example 10 100 40 example 11 30 70 30 example 12 3030 40 30 example 13 100 100 examples 14-19, 100 45 comparative examples1-3

[0116] TABLE 2 conductive filler corrosion preventing additives FePcalcium ion amorphous anti-settling max max max aluminum exchangemagnesium zinc calcium agent resin/curing agent 12 μm 16 μm 22 μm Zntriphosphate silica silicate molybdate borosilicate fumed silica example1 48 40 10 2 example 2 43 50 5 2 example 3 38 50 10 2 example 4 23 50 252 example 5 33 55 10 2 example 6 38 50 10 2 example 7 38 50 10 2 example8 38 50 10 2 example 9 38 50 10 2 example 10 38 50 10 2 example 11 38 5010 2 example 12 38 50 10 2 example 13 38 50 10 2 comparative 38 50 10 2example 1 example 14 53 35 10 2 example 15 28 60 10 2 example 16 46 50 22 example 17 18 50 30 2 example 18 38 50 10 2 example 19 38 50 10 2comparative 38 50 10 2 example 2 comparative 38 50 10 2 example 3

[0117] TABLE 3 corrosion formability weldability resistance example 1 ⊚◯ ⊚ example 2 ⊚ ⊚ ◯ example 3 ⊚ ⊚ ⊚ example 4 ◯ ⊚ ⊚ example 5 ◯ ⊚ ⊚example 6 ⊚ ⊚ ◯ example 7 ⊚ ⊚ ⊚ example 8 ⊚ ⊚ ⊚ example 9 ⊚ ⊚ ⊚ example10 ⊚ ⊚ ⊚ example 11 ⊚ ⊚ ⊚ example 12 ⊚ ⊚ ⊚ example 13 Δ ⊚ ⊚ comparativeexample 1 X ⊚ ⊚ example 14 ⊚ Δ ⊚ example 15 Δ ⊚ ⊚ example 16 ⊚ ⊚ Δexample 17 Δ ⊚ ⊚ example 18 Δ ⊚ ⊚ example 19 Δ ⊚ ⊚ comparative example 2⊚ ⊚ X comparative example 3 ⊚ ⊚ X

What is claimed is:
 1. A resin coated metal sheet comprising: a metalsheet; and a resin layer comprising an epoxy resin, said resin layerbeing formed on said metal sheet, wherein said resin layer contains ironphosphide; at least one selected from the group consisting of aluminumtriphosphate, calcium ion exchange silica and amorphous magnesiumsilicate compound; and a curing agent.
 2. The resin coated metal sheetaccording to claim 1, wherein said metal sheet is a galvanized steelsheet.
 3. The resin coated metal sheet according to claim 1, whereinsaid epoxy resin is at least one of a urethane modified epoxy resin anda dimer acid modified epoxy resin.
 4. The resin coated metal sheetaccording to claim 1, wherein the content of said iron phosphide is 40to 55 wt %, and the content of said at least one selected from the groupconsisting of aluminum triphosphate, calcium ion exchange silica andamorphous magnesium silicate compound is 5 to 25 wt %.
 5. The resincoated metal sheet according to claim 1, wherein the maximum particlediameter of said iron phosphide is 15 μm or less.